The federal judge overseeing the Microsoft Corp antitrust case said on Tuesday that she wants to see a version of the Windows operating system that has removable features.

Over the objections of Microsoft, U.S. District Judge Colleen Kollar-Kotelly said she would allow nine states seeking stiff sanctions against the company to have a computer expert demonstrate a version of Windows he has developed that can be customized. Kollar-Kotelly scheduled the presentation for May 15.

The non-settling states told the judge that Virginia-based computer testing consultant, James Bach, had built his modular version of Windows using Microsoft's own technology. Bach, who has worked as a contractor for Microsoft, had created the new version using Windows XP Embedded, a commercial version of Windows designed for specialty devices such as cash registers and automatic teller machines.

Bach will testify that his modular version of Windows was "robust and reliable," Kollar-Kotelly said, citing the states' submission. The states named Bach as one of two witnesses they want to call at the end of the case to rebut some of Microsoft's arguments. Microsoft attorneys strongly objected, saying the states should have brought Bach into the case earlier when they were presenting their initial case. Kollar-Kotelly agreed in part. She said the states' attorneys hired Bach in February, but had made a "tactical decision" not to call him earlier in the case.

But the judge said it was important to hear from someone who had actually "sat down and tried" to create a version of Windows that could be customized. "I'm going to allow Mr. Bach's testimony primarily for the reason that I think the information should be presented to the court," Kollar-Kotelly said. "I should have it."